Main reference: A.Belyaev, N.Christensen,A.Pukhov.
"CalcHEP 3.4 for collider physics within and beyond the Standard Model",
Computer Physics Communications 184 (2013), pp. 1729-1769
DOI information: 10.1016/j.cpc.2013.01.014
arXiv:1207.6082

Old publications
A.Pukhov e-Print Archive: hep-ph/0412191
A.Pukhov et al, Preprint INP MSU 98-41/542,arXiv:hep-ph/9908288

Lectures: HEP TOOLS PhD lectures